Handle for endodontic instrument



April 26, 1966 D. M. NOSONOWITZ 3,247,594

HANDLE FOR ENDODONTIC INSTRUMENT Filed March 27, 196 3 l INVENTOR DAVID M. NOSONOWITZ WMQM ATTORNEY United States Patent 3,247,594 HANDLE FOR ENDODONTIC INSTRUMENT David M. Nosonowitz, Martin Road, Pleasant Valley, N.Y. Filed Mar. 27, 1963, Ser. No. 268,346 4 Claims. (Cl. 3257) This invention relates to dental instruments, and more particularly to an improved handle construction for use with hand-manipulated instruments used in root canal therapy, and to the combination of such a handle with an endodontic instrument such as a broach or bit.

In the treatment of dental disorders, such as abcessed teeth, it is frequently necessary for the dentist to completely remove root canal tissue from a tooth being treated. This is done by manually introducing a needlelike root canal instrument or broach into the root canal of the tooth, and manipulating the instrument to remove the diseased tissue. This is a very delicate operation in which very sensitive tactile discrimination is required once the bit or shaft of the dental broach has been introduced into the root canal of the tooth. The dentist must rely entirely upon the tactile sense of his fingertips to determine what is taking place in the root canal as he introduces the broach into the root canal and as he manipulates the broach to accomplish the removal of the diseased tissue.

Dental broaches of the prior art have been provided at the outer end thereof with handles of generally cylindrical shape which are heavy and cumbersome and which due to their generally cylindrical shape do not conform to the natural surface anatomy of the dentists fingertips in such manner as to provide the tactile discrimination necessary for best performance of the root canal therapy. As pressure is applied to the terminal one-third of the volar surface of the terminal phalanges of the thumb and forefinger against the handle of the instrument, the tactile sense of the dentist decreases. With endodontic handles of the prior art, the degree of pressure required is such as to cause a decrease in the tactile sense which results in less control by the dentist of the manipulation of the instrument, and slipping of the instrument from the fingertips of the dentist.

Accordingly, it is an object of this invention to provide an improved handle construction for endodontic instruments used in root canal therapy, in which the handle conforms to the surface anatomy of the fingertips of the dentist.

A further object of the invention to provide a handle construction for endodontic instruments which provides greatly increased tactile discrimination as compared to prior art handles for such instruments.

A still further object of the invention is to provide a handle for endodontic instruments which permits the instrument to be controlled and manipulated with greater safety and with the application of less pressure than prior art handles for endodontic instruments.

Another object of the invention to provide a handle for endodontic instruments which is so constructed and contoured as to minimize the possibility of the instrument slipping from the fingertips of the dentist.

Still another object of the invention to provide a handle for endodontic instruments having a plurality of differently contoured surfaces adapted for different types of manipulations in the performance of root canal therapy.

Still another object of the invention is to provide in combination with an endodontic broach or bit a handle contoured in a manner which facilitates the manipulation of the broach selectively with either a rotary or a non-rotary motion and with increased tactile discrimination as compared to endodontic instrument handles of the prior art.

Patented Apr. 26-, 1966 In achievement of these objectives, there is provided in accordance with this invention a handle for an endodontic instrument, including four side wall surfaces each of which has a concave contour conforming to the surface anatomy of the dentists fingertips, which concave surfaces permit the handle to be held by the terminal one-third portion of the volar surfaces of the terminal phalanges of the thumb and forefinger with considerably less pressure than is required using endodontic instrument handles of the prior art. The handle is provided with one pair of opposing surfaces which terminate at the upper end of the handle in flat, parallel upper rims, this pair of surfaces having a concave contour both in the direction of the longitudinal axis of the handle and in a direction perpendicular to the longitudinal axis. This first pair of surfaces is adapted to be engaged by the thumb and forefinger of the dentist when the dental instrument is to be inserted into and manipulated in the root canal without any rotation of the instrument. The handle is also provided with another pair of surfaces which are concave in the direction of the longitudinal axis of the handle, but of convex shape in a direction perpendicular to the longitudinal axis of the handle. The second pair of surfaces is adapted to be held by the thumb and forefinger of the dentist when limited rotation of the dental instrument is required during the root canal therapy.

Further objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a fragmentary sectional elevation view of a tooth and adjacent regions, illustrating the use of a dental broach equipped with the improved handle of the invention;

FIG. 2 is a perspective view of the improved handle of the invention;

FIG. 3 is another perspective view of the improved handle of FIG. 2, viewed from a different perspective angle than in the view of FIG. 2;

FIG. 4 is a top plan view of the handle of the invention;

FIG. 5 is a view in front elevation of the handle of the invention;

FIG. 6 is a view in side elevation of the handle of the invention;

FIG. 7 is a view in vertical section, taken along line 77 of FIGS. 4 and 6;

FIG. 8 is a view in vertical section taken along line 88 of FIGS. 4 and 5;

FIG. 9 is a view in horizontal section taken along line 9-9 of FIG. 6 and illustrating the surfaces of the handle which are engaged by the thumb and forefinger of the dentist for limited rotation of the dental instrument in the root canal; and

FIG. 10 is a view, also taken substantially along line 99 of FIG. 6, and illustrating the surfaces of the handle which are engaged by the thumb and forefinger of the dentist when the dental broach or instrument is received in the root canal of the tooth without rotation.

Referring now to the drawing, the handle for the endodontic tool is generally indicated at 10. An endodontic tool such as a broach 12 is rigidly secured in the lower end of the handle 10 in any suitable manner. Breach 12 is preferably permanently fixed to the handle 1%, although it is within the scope of this invention to use the handle ill with interchangeable dental broaches 12.

The endodontic tool, such as broach or hit 12, may assume various shapes and forms and may be of any of hard plastic material, and includes a flat top surface 14' bounded on a first pair of opposite sides by flat parallel upper rims or walls 16A and 16B which may, for example, be spaced apart by a distance of approximately 5 mm. and which may extend downwardly from the upper surface 14 in the direction of the longitudinal axis of the handle for a distance of approximately 1.5 mm. The top surface 14 is bounded on its second pair of opposite sides by a pair of convex rims 18A and 18B, respectively, which may lie on arcs of a circle drawn from the center of the surface 14 and having a diameter of approximately 6 mm., for example. The convex rims 18A and 183 may extend downwardly from the upper surface 14 for an axial distance of the order of magnitude of approximately 1.5 mm.

The handle is provided below the respective flat rims 16A and 16B with a pair of oppositely disposed surfaces 20A and 20B which are of concave contour from the upper to the lower boundary thereof, or in the direction of the longitudinal axis of the handle. The surfaces 20A and 208, in addition to being of concave contour in the direction of the longitudinal axis of the handle, are also of concave cross section inplanes perpendicular to the longitudinal axis of the handle. Concave surfaces 29A, 20B are bounded on their upper ends by the lower boundary of fiat rims 16A and 16B, respectively which aid the dentist in orienting his fingers relative to surfaces 20A, 20B. Surfaces 20A and 26B are bounded at their lower ends by the lower tapered end of the handle, to be described.

The concave contour of the oppositely disposed surfaces 29A and 203, both in the direction of the longitudinal axis of the handle, and in a direction transverse to the longitudinal axis, adapts these surfaces to receive the tips of the thumb and forefinger of the dentist, particularly, the terminal one-third of the volar surface of the terminal phalanges of the thumb and forefinger. The oppositely disposed surfaces 20A and 20B are engaged by the fingertips of the dentist particularly for manipulations of the dental broach 12 in which the instrument is to be moved into and manipulated inside of the root canal 25 of the tooth 23 (FIG. 1) without any rotation being imparted to the instrument during the insertion into and engagement with the root canal. The surfaces 20A and 20B are of particular use where the tool 12 secured to the handle 10 is of the type, for example, which do not normally have rotary motion imparted thereto, such as rattail files, rasps, and planers.

The handle also has oppositely disposed surfaces 22A and 22B which lie below the convex rims 18A and 18B and which are bounded at the lower ends thereof by tapered end 26 of the handle. The oppositely disposed surfaces 22A and 22B are of concave contour from the upper to the lower end thereof, or in a direction extending in the direction of the longitudinal axis of the handle, but are of convex contour in planes transverse or perpendicular to the longitudinal axis of the handle. The concave contour of the surfaces 22A and 2213 in a direction longitudinally of the handle, conforms the surfaces 22A and 223 to the surface anatomy of the dentists fingertips in a manner similar to the longitudinal concavity of the surfaces 20A and 20B previously described. The convex curvature of the surfaces 22A and 2213 in a peripheral direction or in planes transverse to the longitudinal axis of the handle facilitates the manipulation of the handle for limited rotation thereof. Such limited rotary motion may be required in certain manipulations of the dental tool in the course of root canal therapy. The convex surfaces 22A and 22B and convex rims 18A, 18B are adapted to be engaged by the tips of the thumb and forefinger of the dentist when limited rotary motion of the broach is required, and are particularly useful Where the dental broach 12 which is secured to the handle Iii is of a type such as a reamer or standard file which normally has limited rotary motion imparted thereto during its use in root canal therapy.

The opposite fiat rims 16A and 16B and the oppositely disposed convex rims 18A and 18B intersect each other in four unrounded or sharp corners 24 which aid in orienting the dentists approach to the reinsertion of a curved broach 12 conforming to a curved root canal. All other merging surfaces, such as the merger of the oppositely disposed surfaces 20A and 2013 with the surfaces 22A and 22B are rounded.

The lower boundaries of the four surfaces 20A, 20B, 22A. and 22B as previously mentioned are defined by the upper peripheral boundary of the lower end of the handle, generally indicated at 26, which has its surfaces tapered downwardly at an angle of substantially 45 degrees to the central longitudinal axis of the handle, the tapered lower end 26 terminating in a small, short fiat end surface 28 which lies in a plane substantially perpendicular to the longitudinal axis of the handle.

The handle it) may have an overall height from its fiat upper end surface 14 to its fiat lower end surface 28 of the order of magnitude of 7.7 mm.-9.6 mm., for example. The lower tapered end portion 26 may have a height of approximately 2 mm., for example. It will be understood that any dimensions given in the specification are by way of example only and are not intended to be limiting.

All surfaces of the handle are provided with a dull brush finish to eliminate glare and to increase surface friction against the fingertips.

It can be seen from the foregoing that there is provided in accordance with this invention an improved handle construction for use in combination with handmanipulated endodontic instruments used in root canal therapy. The concave contours of the four side wall surfaces of the handle conform comfortably to the surface anatomy of the terminal one-third of the volar surface of the terminal phalanges of thumb and forefinger of the dentist, and permit the dentist to manipulate the instrument with the application of less pressure than is required with enclodontic instrument handles of the prior art. Since less pressure is required to hold the endodontic handle of the invention, the tactile sense of the dentists fingertips is much greater than with handles of the prior art which require greater pressure by the fingertips. Furthermore, the concave curvature of the four side wall surfaces of the handle greatly minimizes the possibility of the instrument slipping from the fingertips of the dentist. The handle also is provided with opposite pairs of surfaces which adapt the dental instrument selectively for either non-rotating or rotating engagement of the dental broach with the root canal of the tooth.

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as my invention is:

1. A handle for an endodontic instrument comprising a straight body having a first pair of oppositely disposed surfaces each of which is concave in both the longitudinal and transverse directions of said body, and a second pair of oppositely disposed surfaces each of which is concave in the longitudinal direction of said body and convex in the transverse direction of said body, each of said pairs of surfaces being adapted to receive a portion of the volar surface of the terminal phalanges of a pair of human fingers.

2. A handle for an endodontic instrument comprising a body having an outer end bounded on a first pair of opposite sides thereof by two straight rim portions and on a second pair of opposite sides by two convex rim portions, 21 first pair of oppositely disposed surfaces each respectively extending longitudinally from a correspond-- ing one of said straight rim portions for a substantial portion of the length of said handle, each of said surfaces of said first pair being of concave contour in both the longitudinal and transverse directions of said body, a second pair of oppositely disposed surfaces each respectively extending longitudinally from a corresponding one of said convex rim portions for a substantial portion of the length of said handle, each of said surfaces of said second pair being of concave contour in a direction longitudinally of said handle and of convex contour in a direction transverse of the length of said handle, each surface of'each of said pairs of surfaces being adapted to receive a portion of the volar surface of the terminal phalange of one finger of a pair of human fingers.

3. An endodontic instrument comprising a straight handle having a first pair of oppositely disposed surfaces each of which is concave in both the longitudinal and transverse directions of said body and a second pair of oppositely disposed surfaces each of which is concave in the longitudinal direction of said body and convex in the transverse direction of said body, each of said pairs of surfaces being adapted to receive a portion of the volar surface of the terminal phalanges of a pair of human fingers, and an endodontic tool secured to said handle.

4. An endodontic instrument comprising a straight handle having an outer end bounded on a first pair of opposite sides thereof by two straight rim portions and on a second pair of opposite sides by two convex rim portions, a first pair of oppositely disposed surfaces each respectively extending longitudinally from a corresponding one of said straight rim portions for a substantial portion of the length of said handle, each of said surfaces of said first pair being of concave contour in both the longitudinal and transverse directions of said body, a second pair of oppositely disposed surfaces each respectively extending longitudinally from a corresponding one of said convex rim portions for a substantial portion of the length of said handle, each of said surfaces of said second pair being of concave contour in a direction longitudinally of said handle and of convex contour in a direction transverse of the length of said handle, each surface of each of pairs of surfaces being adapted to receive a portion of the volar surface of the terminal phalange of one finger of a pair of human fingers, and an endodontic tool secured to said handle and extending from an end of said handle opposite said outer end.

References Cited by the Examiner UNITED STATES PATENTS 1,402,229 1/ 1922 Hauptmeyer 32-57 1,527,028 2/1925 Daniel 132-89 2,158,593 5/1939 Scrimgeour 128-221 2,219,089 10/1940 Everett 128221 X 2,520,355 8/1950 Bell 30-340 FOREIGN PATENTS 434,028 1/ 1912 France.

RICHARD A. GAUDET, Primary Examiner.

JAMES W. HINEY, IR, Assistant Examiner. 

1. A HANDLE FOR AN ENDODONITIC INSTRUMENT COMPRISING A STRAIGHT BODY HAVING A FIRST PAIR OF OPPOSITELY DISPOSED SURFACES EACH OF WHICH IS CONCAVE IN BOTH THE LONGITUDINAL AND TRANSVERSE DIRECTIONS OF SAID BODY, AND A SECOND PAIR OF OPPOSITELY DISPOSED SURFACES EACH OS WHICH IS CONCAVE IN THE LONGITUDINAL DIRECTION OF SAID BODY AND CONVEX IN THE TRANSVERSE DIRECTION OF SAID BODY, EACH OF SAID PAIRS OF SURFACES BEING ADAPTED TO RECEIVE A PORTION OF THE VOLAR SURFACE OF THE TERMINAL PHALANGES OF A PAIR OF HUMAN FINGERS. 